By Julie Makinen, Los Angeles Times
BEIJING — An Australian ship towing a U.S. Navy “pinger” locator has twice picked up sustained signals that may be from missing Malaysia Airlines Flight 370’s “black boxes,” and searchers are likely to deploy an underwater exploratory vehicle soon to look for wreckage, authorities said Monday.
The first acoustic event detected by Ocean Shield lasted two hours and 20 minutes, and the second lasted 13 minutes, said Australian Air Chief Marshal Angus Houston, who is coordinating search efforts from Perth, Australia.
“We are encouraged we are very close to where we need to be,” said Houston, describing the finding as the best lead so far in the quest to find the missing Boeing 777. However, he urged the media and the public to treat the news “cautiously and responsibly.”
Houston said that for perhaps the next 24 hours, the Ocean Shield would continue passing over the area where the signals were detected, trying to get a better fix on the actual location.
Commodore Peter Leavy of the Australian navy said if the crew detects the signal a third time, “that will be the trigger to launch the underwater vehicle with the sonar” to explore for wreckage.
With the search in its 31st day and batteries on the so-called black box pingers nearing the end of their expected life, searchers may decide to deploy the underwater search vessel regardless.
Cmdr. William Marks of the U.S. 7th Fleet, who is aboard the Ocean Shield, said the towed pinger locator was only about 325 yards deep when it began detecting the pings at one-second intervals. “We were not overly optimistic,” he told CNN by satellite phone from the ship.
But after lowering the towed pinger locator to about 1,530 yards, the crew was able to get a hold of the signal for more than two hours.
Marks noted that if the signal was coming from a black box, the signal would get stronger and then fade as the locator passed over the site. “That’s what happened,” he said.
Crews then did a course change and passed back over the area, lowering the towed pinger locator to about 3,280 yards, which Marks called the “optimal depth.” Crews were able to pick up a signal for about 15 minutes, he said.
On Saturday, China’s state-run media said crews with the patrol ship Haixun 01 had briefly picked up 37.5 MHz pulses — the same frequency emitted by an airplane flight data recorder pinger — on Friday and Saturday in the Indian Ocean, at a latitude of 25 degrees south and longitude of 101 degrees east. They were using less sophisticated equipment that is designed for divers to search at depths up to 600 feet.
Australian officials said Sunday that ocean depths in the area where the Chinese crews reported detecting the pulses could be up to about 4,920 yards. “It would typically not be used to … look for something that is thousands of meters deep in the ocean. That’s not what it is designed to do,” Thomas Altshuler, vice president and group general manager of Teledyne Marine Systems, said in a phone interview. “But it is possible to detect at this depth…The physics would say that it is possible.”
Until late Saturday, Australian authorities coordinating the search for the plane, which disappeared March 8 on a flight from Kuala Lumpur to Beijing, had indicated that only two ships in the search fleet — the Ocean Shield and the British survey ship Echo — had carried equipment that could detect transmissions from a black box.
Altshuler said while the Teledyne Benthos equipment can detect pings, it does not record them and save them for later, unless the device had been modified by the Chinese.
“The physics of how sound propagates through the water is very complex,” Altshuler said. “Like with a cellphone, you walk around your house and the signal fades in and out…There’s an analogous effect in the ocean.”
The challenging search for Flight 370, Altshuler said, points up the fact that airplane black boxes carry only very basic technology, even though much more advanced equipment that could make such searches less difficult is available.
For instance, he said, aviation authorities could mandate that black box pingers carry 90-day batteries, instead of the 30-day ones that are standard now.
“I don’t know why government or policy is done the way it is,” he said. “There is technology that is readily available that could make the search of something like this easier — from the top side and what’s on the (airplane).”
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